Air conditioning apparatus



AprlZQ, 1969 R. A.` CHURCH 3,441,080

AIR CONDITIONING APPARATUS Filed oct. 17, 1967 sheet of 2 FIG /0 RICHARD A. CHURCH.

f qisa BY 1 69 /W "4 ATTORNEY.

l l l E 70 INVENTOR. y l l I l E April 29, 1969 R, A, CHURCH 3,441,080

AIR CONDITIONING APPARATUS Filed OCT. 17, 1967 sheet 2 @f2 To OUTDOOR TEMP. Tn

INVENTOR. RICHARD A. CHURCH.

ATTORNEY.

United States Patent O "ice 3,441,080 AIR CONDITIONING APPARATUS Richard A. Church, North Syracuse, N.Y., assignor t Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Oct. 17, 1967, Ser. No. 675,958 Int. Cl. F25b 13/00 U.S. Cl. 165-2 8 Claims ABSTRACT 0F THE DISCLOSURE A medium or high pressure air conditioning system and method of operation where a variable volume of primary air is distributed to each room or area being conditioned `during periods of cooling and/ or ventilation in accordance with demand conditions of each individual roo-m or area served. During periods of heating, the variable volume control is negated and a constant volume of primary air is directed to all'rooms or areas served.

Background of the invention This invention relates to air conditioning systems and, more particularly, to air conditioning systems of the medium or high pressure type and their methods of operation.

In air conditioning systems of the type where individual streams of preconditioned primary air and secondary air are used to condition each room served, the primary air is usually delivered in a constant volume. The temperature of the primary air, however, is varied to offset transmission gains or losses. On the other hand, the volume of secondary air, which is held at a susbtantially constant temperature, is continuously changed to accommodate the changing demands of each individual room conditioned. Since the amount of primary air discharged into each room must necessarily be relatively large to accommodate the maximum heating load anticipated during Winter operation to maintain ideal room temperatures, overcooling may result during summer operation even though the volume of secondary air is automatically reduced with decreased demand.

To prevent overcooling, the primary air can be heated in accordance with a preset schedule based on outdoor temperature conditions during summer operating conditions. The secondary air is then relied upon to meet not only the natural cooling load of the area being conditioned, but the amount of cooling available is substantially reduced by the primary air being heated. Heating or reheating of the primary air under these circumstances decreases over-all system eiciency.

It is a principal object of the present invention to provide a new and improved medium or high pressure air conditioning system and method of operation.

It is a further object of the present invention to provide, in air conditioning systems of the type having both primary and secondary conditioned air streams with means to vary during cooling the volumes of primary and secondary air in accordance with cooling demands of the individual areas conditioned, a control mechanism that, on a requirement for heating, overrides the primary air volume varying means to cause a substantially constant volume of heated primary air to be discharged into all areas while continuing to supply secondary air in accordance with the demands of each individual area.

It is an object of the present invention to provide an improved method for operating an air conditioning system where, during summer operating conditions, the quantity of cool primary and secondary air discharged into each room served is varied in response to the particular 3,441,080 Patented Apr. 29, 1969 demands of each room and where, during winter operating conditions, a xed quantity of heated primary air is discharged into all rooms served regardless of individual room demand while the quantity of cool secondary air continues to be varied with individual room demand.

Summary of .the invention This invention relates to an apparatus including fan means for conditioning a plurality of rooms, comprising in combination lirst conduit means for distributing primary air treated to offset transmission gains or losses to each room, vsecond conduit means for distributing secondary air at a substantially constant temperature to each room, secondary air control means adapted to vary the volume of secondary air discharged into each room in accordance with the individual temperature conditions of each room; and primary air control means including a first control means adapted to vary the volume of primary air discharged into each room in accordance with the individual temperature conditions of each room, and a second control means adapted at a preset outdoor temperature condition to negate the rst control means and discharge a substantially constant volume of lprimary lair into all rooms irrespective of room temperature conditions.

The invention further relates to a method for yeararound conditioning a multi-room building, in which the steps consist in conditioning return air to compensate for transmission gains or losses to provide a source of primary air, providing air, preferably, Ventilating air, at a substantially constant relatively cool temperature as a source of secondary air; during winter operating conditions, supplying varying amounts of secondary air to each one of the 'rooms in accordance with the individual cooling demands of each one of the rooms while supplying a substantially constant volume of primary air to all of the rooms; and, during summer operating conditions, supplying varying amounts of both primary and secondary air to each one of the rooms in accordance with the individual cooling demands of each one of the rooms.

Brief description of the drawings FIGURE 1 is a schematic diagram showing the conduit type air conditioning system of the present invention;

FIGURE 2 is a sectional View illustrating an voutlet terminal of the system shown in FIGURE 1;

FIGURE 3 is a view showing a pneumatic control a1- rangement for the system shown in FIGURE l; and

FIGURE 4 is a graph comparing a typical prior art system primary air heating schedule with that of the present invention.

Referring to FIGURE 1 of the drawing, an air conditioning system 10 incorporating the control arrangement of the present invention is shown. Air conditioning system 10, which may be described as a central station type, includes an air conditioning equipment section, designated generally by the numeral 12, and a conduit system 14, 15 for conducting conditioned primary and secondary air to each of the areas or rooms 18 being conditioned. Equipment section 12 may be in the basement or on the roof of a building. For the purposes of this description, primary air may comprise air returned from the areas being conditioned and treated in section 12 while secondary air may comprise fresh or Ventilating air drawn from the outdoors or a mixture of outdoor and return air and treated in section 12.

The conditioning apparatus for the primary air prefera'bly includes a suitable lter 24, cooling or dehumidifying coil 25, and heating or reheating coil 26 arranged in series ow relationship and encased within a suitable housing 28. Housing 28 is connected by duct 30 with return air and exhaust fan 32. The inlet 32 of fan 32 is connected by suitable means (not shown) with the areas or rooms 18 being conditioned. Preferably, inlet air control vanes 33 are provided to vary the ilow of air through fan 32. lExhaust duct 36 having dampers 37 therein connects duct 30 with the outdoors. Dampers 37 control the volume of return air discharged to the atmosphere.

Housing 28 connects with primary air fan 40. Conduit means 14 conveys primary air from fan 40 to the areas of rooms 18 being conditioned. Run-outs 42 lead to the individual rooms 18. Run-outs 42 each have at least one outlet terminal 44.

The secondary air conditioning apparatus preferably includes a suitable lter 45 and a cooling or dehumidifying coil 46 arranged in series ow relationhsip and encased within a suitable housing 47. Housing 47 is connected through damper 48 with the outdoors. Bypass duct 49 having dampers 50 connects return air duct 30 with housin-g 47.

Housing 47 is connected with the inlet of secondary air fan 52. Preferably, adjustable vanes 53 are provided to vary the flow of secondary air through fan 52.

Conduit means conveys air from fan 52 to the areas or rooms 18 being conditioned, run-outs 56 being provided to the individual rooms 18. Run-outs 56 have one or more outlet terminals 58.

Cooling or dehumidifying coils 25, 46 are controlled by pneumatic type control valves 91, 105 interconnected by lines 91', 105 to a suitable source of chilled heat exchange medium, such as refrigeration machine 59. A circulating pump 60 for the chilled medium may be provided. Heating or reheating coil 26 is connected by pneumatic type control valve 62 with a suitable heating medium such as steam.

Primary air terminals 44 and secondary air terminals 58 regulate the volume of primary and secondary air discharged into the room 18 being served in response to temperature conditions of the room 18. The general construction of terminals 44, 58 is shown in my Patent No. 3,143,292, granted Aug. 4, 1964.

Referring to FIGURE 2, each terminal 44, includes a low velocity plenum chamber 64 and discharge slots 65. An inflatable bellows 66 between plenum chamber 64 and slots 65 controls the quantity of air discharged through the terminal. Supply air drawn from run-outs 42, 56 enters conduit portion 42 of terminals 44, 58 respectively and passes through openings 64 into plenum 64, being discharged into the area being treated through discharge slots 65. A portion of the supply air from portions 42 passes through a suitable pressure regulating device 67 and line 70 to bellows 66. A suitable thermostatically controlled valve 68 regulates pressure in the bellows 66 by bleeding controlled amounts of pressure air through port 69 from line 70 in response to temperature conditions within room being treated. Changes in pressures within bellows 66 effectuates a corresponding change in bellows size which in turn varies the volume of air discharged from slots 65.

`Primary air terminals 44 are provided with a second bleed port 72 regulated by thermostatic control 73 responsive to temperature conditions of the primary air in conduit means 14. As shown in FIGURE 2, the bulb 73 of control 73 may 4be placed in conduit portion 42 of a primary air terminal. Control 73 opens port 72 when the primary air is heated and the temperature thereof rises above a predetermined temperature. With port 72 open, bellows 66 collapses and terminal 44 discharges a constant volume of primary air into the room 18. Terminals 58 are identical to terminals 44 with the exception thermostatic control 73 is eliminated on terminal 58.

In the control arrangement of FIGURE 3, compressed air from a suitable source (not shown) is supplied through line 75 to a normally closed electro-pneumatic relay 76 through which the compressed air passes to the control mechanism for the system primary air conditioning apparatus. Relay 76 opens when primary air fan 40 is actuated.

Signal pressure air from relay 76 is transmitted through line 77, control valve 78, and heating relay 79 to the operating mechanism of heating valve 62.

Control valve 78 responds to temperature conditions of the primary air in conduit means 14 as sensed by feeler 78 thereof. Where temperature conditions of the primary air are below a preset temperature, the signal output pressure of valve 78 is Zero. As temperatures of the primary air in conduit means 14 rise above the instantaneous preset response temperature of valve 78, signal output pressures from valve 78 increase.

Valve 78 includes a suitable biasing mechanism adapted to vary the preset response temperature of valve 78 in accordance with changes in outdoor temperatures sensed 'by outdoor temperature controller 84, as will be more apparent hereinafter.

Heating relay 79 normally vents the operating mechanism of heating valve 62 to the atmosphere. The actuating mechanism 79 of relay 79 is connected by line 85 with the output of controller 84. At predetermined signal pressure, relay 79 operatively connects the output side of control valve 78 to the operating mechanism of heating valve v62.

Controller 84 is adapted to vary output signal pressures in accordance with changes in outdoor temperature conditions as sensed by feeler 84 thereof. Where outdoor temperatures are above a preset minimum, the output signal pressure of controller 84 is zero. When outdoor temperatures are below the preset response temperature of controller 84, controller 84 provides, in lines 82, 85 and 95, an output pressure signal whose intensity varies in accordance with outdoor temperature conditions.

Signal pressure air is transmitted through temperature responsive cooling control valve 89 and cooling relay 90 to the operating mechanism of cooling valve 91. Feeler 89 of valve 89 is arranged in the primary air conduit means 14. Where temperature conditions of the primary air are below a preset temperature, the output signal pressure of valve 89 is zero. As temperatures of the primary air increase above the preset response temperature of valve 89, the signal output pressure of valve 89 increases.

Cooling relay 90 operatively connects the operating mechanism of cooling valve 91 with the output of control valve 89. At a preset pressure signal, relay 90 vents the operating mechanism of valve 91 to the atmosphere, closing valve 91.

The output signal of heating-cooling controller 93 is fed by line 94 to the operating mechanism 90' of cooling relay 90. Line 95 connects the operating mechanism of controller 93 with outdoor temperature responsive controller 84. Where outdoor temperature conditions are below the preset response temperature of controller 84, the pressure signal output of controller 84 actuates controller 93, which vents the operating mechanism 90 of cooling relay 90 to the atmosphere, closing valve 91. Where outdoor temperatures are above the preset response temperature of controller 84, the output signal therefrom is zero and controller 93 terminates venting of cooling relay 90. Relay 90 operatively connects the operating mechanism of valve 91 with control valve 89 enabling valve 89 to regulate the position of cooling valve 91 in response to primary air temperature conditions.

A control valve 100, which is arranged to open on start up of the secondary air fan 52, feeds signal pressure air through line 102 and cooling control valve 104 to the actuating mechanism for secondary air cooling valve 105. Control valve 104 responds to temperature conditions of the secondary air in conduit means 15 as sensed by feeler 104 thereof. Where temperatures of the secondary air -are below the preset response temperature of control valve 104, valve 104 vents the actuating mechanisrrr of cooling valve 105 to the atmosphere. When sccondary air temperatures are above the preset response temperature setting of control valve 104, valve 104 applies a pressure signal to the operating mechanism of valve 105 to open valve 105 and admit cooling medium to coil 46.

The output signal pressure from control valve 104 is transmitted via outdoor air temperature responsive control 108 to the drive mechanism for exhaust, fresh air and return air dampers 37 48 and 50 respectively. Where outdoor temperature conditions are above the preset response temperature of control 104, the output pressure signal from valve 104 is transmitted through valve 108 to the damper drive mechanism to change the relative positions of dampers 37, 48, 50 and thereby vary the ratio of exhaust air, fresh air, and recirculated air in the system.

A pair of pressure responsive controls 116, 117, arranged in primary and secondary air conduit means 14, respectively, provide signal pressure air to the actuating means 34, 54 for the return air and secondary fan inlet vanes 33, 53 respectively. As static pressure conditions in the conduit means 14, 15 vary, the actuating means 34, 54 change the position of vanes 33, 53 respectively to vary the quantity of Iair entering fans 32, 52 respectively.

Operation On actuation of the primary air and secondary air fans 40, 52 respectively, control valves 76, 100 open to feed pressure control air to the control arrangement shown in FIGURE 3. It is assumed that both the source of cooling medium, refrigeration machine 59 with cooling system pump 60, and the source of heating medium are operational.

Where outdoor temperatures are relatively high, the pressure output signal of controllers 84, 108 is substantially zero. Primary air heating relay 84 therefore vents the operating mechanism for heating valve 62 to the atmosphere and valve 62 is closed. Signal pressure air fed through heating-cooling controller 93 to the operating mechanism of cooling relay 90 actuates relay 90. Relay 90 operatively connects cooling control valve 89 with the operating mechanism of cooling valve 91. Where primary air temperatures are above the preset response temperature of valve 89, the output signal generated by valve 89 actuates the operating mechanism of valve 91 to open valve 91 and permit cooling medium to ow through coil 25 of the primary -air conditioning apparatus 28.

At the same time secondary air cooling control 104 regulates operation of cooling valve 105 in accordance with temperature conditions of the secondary air in conduit means 16 to control ow of cooling mediunr to coil 46 of the secondary air cooling apparatus 47. Control 108 regulates the relative positions of exhaust, fresh air, and return air dampers 37, 48, 50 respectively in accordance with outdoor temperature conditions when outdoor temperatures are above the preset temperature response setting of control 108.

Primary air and secondary air terminals 44, 58 control the quantity of primary air and secondary air discharged into each room 18 in accordance with the individual temperature requirements of the room. As described heretofore in conjunction with FIGURE 2 of the drawings, the thermostatic control valve 68 of terminals 44, 58 regulates pressure conditions within bellows 66 in response to room temperature conditions to control the effective s1ze of the terminal outlet 65. Since temperature conditions of the primary air are, due to the cooling effect of coil 25, relatively low, thermostatic control valve 73 of primary air termin-als 44 holds port 72 closed.

Varying the elective size of the outlet of terminals 44, `58 in response to changes in room temperature conditions causes pressures within conduit means 14, 15 to vary. Any variation lin pressure in conduit means 14 or 15 is sensed by controller 116 or 117 respectively which, acting through the vane actuating mechanism 34 or 54 varies the position of inlet -vanes 33 or 53. By repositioning of varies 33, 53 the quantity of air passing through fans 40, 52 respectively is adjusted to compensate for changes in the requirements of rooms 18.

Heating or reheating valve 62 at this point is closed and no reheating of the primary air takes place. Any tendency for the system to overcool, which heretofore necessitated wasteful reheating of the primary air, is avoided by the automatic reduction in the amount of primary air discharged into the individual room.

Should outdoor temperatures fall below the preset response temperature of controller 84, the resulting signal pressure output of controller 84 actuates controller 93 to cut off the flow of signal pressure air to cooling relay 90. Cooling relay accordingly vents the operating mechanism of cooling valve 91 to the atmosphere, closing valve 91 to terminate the ow of cooling medium to coil 25. At the same time the pressure signal output of controller 84 triggers heating relay 79 to operatively connect the operating mechanism of valve 62 with heating control valve 78. Additionally, the pressure signal of controller 84 may, depending upon its intensity, reset or change the temperature response setting of valve 78. It is understood that the pressure signal output of controller 84 increases with decrease in outdoor temperature. As the pressure output signal from controller 84 rises, the temperature response setting of controller 84 rises, the temperature response setting of control valve 78 rises.

Where temperatures of the primary air in conduit means 14 are below the instantaneous response temperature setting of control valve 78, the output pressure signal from valve 78 opens valve 62 to admit heating medium to coil 26.

Warmed primary air from coil 26 flows through conduit means 14 and run-outs 42 to terminals 44 and the individual rooms. T hermostatic control valve 73 senses the heated primary air and uncovers bleed port 72 of terminals 44. Opening of bleed port 72 vents bellows 66 to the atmosphere causing bellows 66 to collapse so that terminals 44 thereafter function as constant volume outlets.

As outdoor temperatures decrease, the pressure output signal of controller 84 increases. The increasing pressure output signal raises the temperature response setting of valve 78 to increase the amount of heated medium admitted to coil 26.

Thermostatic control valve 104 regulates the position of secondary air cooling valve 105 in accordance with secondary air temperatures. As long as secondary air temperatures are above the response temperature setting of control valve 104, the secondary air is cooled. It is understood, however, that secondary air outlets 58 vary the quantity of secondary air discharged into the individual rooms 18 in accordance with room temperature conditions.

In FIGURE 4, temperatures of the primary and secondary air are plotted against outdoor ambient temperatures for an exemplary prior art system as well as for the system of the present invention. Temperature of the secondary air, which is held constant in both, is represented as horizontal line at temperature Ts. A second horizontal line 122 at temperature Tr represents the temperature which the systems are designed to maintain.

In the prior art system, primary air temperatures are represented by dotted line 124 which slopes downwardly from a maximum temperature Tm through the point 125 on line 122 at outdoor temperature Tn. Outdoor ternperature Tr1 represents a neutral temperature condition, that is, the same temperature as Tr.

The heat available is a function of both the volume and temperature of the primary air. The maximum air temperature Tm is restricted by practical considerations, and accordingly, the system must 'be designed to handle a volume of primary air which at temperature Tm will meet the maximum design heating load, represented by outdoor temperature To.

In prior art systems, the required volume of primary air may cause overcooling during summer operation. Although the variable volume secondary air terminals 58 will react to lowered room cooling demand and reduce flow of secondary air, overcooling may nevertheless occur. Further, since the secondary air includes fresh air, it is undesirable to stop or greatly curtail the secondary air.

To prevent overcooling and assure adequate volumes of secondary air, the primary air in prior art systems is heated during summer operation as evidenced by segment 124 of dotted line 124, the temperature of the primary air being gradually reduced with increasing outdoor temperatures. The resultant introduction of warmed primary air into the rooms is compensated for by increased amounts of cool secondary air to satisfy room demands.

In the system of the present invention, temperatures of the primary air are represented by line 128 which slopes downwardly from a temperature Th to point 125 on line 122. At outdoor temperature Tn, heating of the primary air in the system of the present invention is terminated by outdoor thermostat 84 as explained heretofore. The temperature of the primary air thereafter approximates the temperature of the secondary air as represented by line 120 and primary air terminals 44 vary the volume of lprimary air introduced into each room in accordance with individual room demand thereby avoiding overcooling of the rooms and obviating the need for heating the primary air. The saving in heat effected by the system of the present invention over the prior art system is represented by shaded area 127 in FIGURE 4.

Additionally, inasmuch as the system of the present invention avoids the problem of overcooling by the primary air during summer operation, the volume of primary air which the system may be designed to handle can be larger and may in fact equal the volume of secondary air. The larger permissible volume of primary air advantageously enables system design temperature Th to be made substantially lower without attendant loss in system elfectiveness.

While I have described preferred embodiments of the present invention, it is understood that this invention may be otherwise embodied within the `scope of the following claims.

I claim:

1. In an air conditioning system for treating an area to be conditioned, the combination of a central station for conditioning a stream of primary air to compensate for transmission gains or losses in the area and for conditioning a stream of secondary air to a substantially constant temperature, at least one terminal in said area for receiving primary air from said central station, at least a second terminal in said area for receiving secondary air from said central station, rst conduit means for supplying primary air from the central station to said first terminal to compensate for transmission gains or losses in the area, second conduit means for supplying secondary air at a substantially constant temperature to said second terminal to compensate for sensible heat gains in the area, air control means controlling the discharge of secondary air from the second terminal and serving to vary the volume of secondary air discharged in the area responsive to temperature conditions in the area, and second air control means controlling the discharge of .primary air from the first terminal, said second air control means including means to vary the volume of primary air discharged in the area responsive to temperature conditions in the area, and means adapted at a predetermined outdoor temperature to negate said rst means to discharge a substantially constant volume of primary air in said area irrespective of temperature conditions in the area.

2. In an air conditioning system, the combination of an apparatus including fan means for conditioning a plurality of rooms, the combination comprising first conduit means for distributing primary air treated to offset transmission gains or losses to each room; second conduit means for distributing relatively cool secondary air at a substantially constant temperature to each room; secondary air control means adapted to vary the volume of secondary air discharged into each room in accordance with individual temperature conditions of each room; and primary air control means including:

(a) first control means adapted to vary the volume of primary air discharged into each room in accordance with individual temperature conditions of each room; and

(b) second control means adapted at a preset outdoor temperature condition to neutralize said first means and discharge a substantially constant volume of primary air into all of said rooms irrespective of room temperature conditions.

3. An air conditioning system according to claim 2 in which means are provided for heating the primary air, control means responsive to said preset outdoor temperature to actuate said heating means, said second means including means responding to increased primary air temperature to negate said first control means so that a relatively constant volume of primary air is discharged into all of said rooms.

4. An air conditioning system according to claim 2 in which fans are provided to supply treated air through said first and second conduit means, and regulating means are provided responsive to static pressure in said conduits to maintain a substantially constant pressure differential in said conduits while the volumes of primary and secondary air discharged into said area is varied.

5. An air conditioning system according to claim 2 in which said first conduit includes an outlet, said second air control means includes expansible means for varying the volume of primary air discharged through said outlet, and means communicating said expansible means with the stream of primary air being supplied to said iirst outlet.

6. In a method of air conditioning a multi-room building, the steps which consist in:

(a) conditioning air returned from areas being treated to compensate for transmission gains or losses from the areas thus providing a source of primary air;

(b) providing air at a substantially constant relatively cool temperature at a source of secondary air;

(c) during winter operating conditions, supplying varying volumes of secondary air to the areas in accordance with individual cooling demands of each of the areas while supplying a substantially constant volume of primary air to all ofthe areas; and

(d) during summer operating conditions, supplying varying volumes of both primary and secondary air to each one of the areas in accordance with the individual cooling demands of each of the areas.

7. A method according to claim 6 which includes the step of changing over from a constant volume supply of primary air to a variable volume supply of primary air, and vice versa, in response to a predetermined outdoor temperature condition.

8. A method according to claim 6 which includes the step of supplying substantially equal volumes of primary air and secondary air at maximum cooling load during summer operation.

References Cited UNITED STATES PATENTS 5/1961 Waterll 165-22 U.S. Cl. XR. 

